Age of Uranium Mineralisation from North Delhi Fold Belt (NDFB): Evidences from U-Pb, Pb-Pb and Sm-Nd Systematics

Abstract

Abstract Results of multi-method geochronological study (U-Pb, Pb-Pb and Sm-Nd), on uranium mineralized rocks along the albitite line in the North Delhi Fold Belt (NDFB, Rajasthan, India) are presented. The Pb-Pb ages obtained, on uranium mineralized core samples, from Rohil uranium deposit, Sikar district, Rajasthan (south western part of NDFB), are 836 ± 5 Ma (Pb Sequential Leaching-PbSL, weighted average of 11 isochron ages), 826 ± 9 Ma (Pb-Pb isochron age on uraninite), 842 ± 18 Ma (U-Pb concordia upper intercept age, on uraninite). Similar ages of uraninites were also obtained from areas close to Rohil uranium deposit i.e. Jahaz (823 ± 10 Ma, U-Pb and 826 ± 14 Ma, Pb-Pb) and Ghateshwar areas (834 ± 14 Ma, U-Pb concordia upper intercept age and 826 ± 25 Ma, Pb-Pb isochron age). The ages of uranium mineralisation (PbSL) further in northeastern part of NDFB i.e. in Gorir area, Jhunjhunu district, Rajasthan, are 827 ± 7 Ma, 818 ± 24 Ma (PbSL) and in Dhancholi area, Mahendragarh Dist., Haryana, are 824 ± 12 Ma (U-Pb) and 824 ± 6.5 Ma (Pb-Pb). The above age data in general indicates age of uranium mineralization as 830 Ma in the NDFB. These ages are consistent with age of uranium mineralization in albitites from Brazil.